(Assigning this to Brandon for now. I'm happy to help out with this, but it'll take some ramping up on mojo/gamepad code.)

This sounds like a correctness issue with the potential for crashes or similar issues. Is anyone working on this?

How does this relate to overall refactoring efforts? 

I'm working on a patch now that makes pose reading threadsafe, so I think the main remaining issue is controller access from multiple threads.

There are some other non-threadsafe usages on initialization, but that's probably lower priority.

Michael, ping on where the patch you reference in Comment 4 is.  

https://codereview.chromium.org/2624633002/ is out for review.

Unless others disagree, we're not seeing this cause any issues in practice, so it's not worth back-porting to M57 at this point.

Sounds like it should get resolved in M58 then.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/4c6465c3b85e664ca700e1c04bebf637c7846243

commit 4c6465c3b85e664ca700e1c04bebf637c7846243
Author: mthiesse <mthiesse@chromium.org>
Date: Wed Feb 01 23:40:17 2017

Refactor GvrDelegate ownership into GvrDelegateProvider and fix more threading violations.

This CL does two main things: It refactors controlling when the GvrDelegate is created and destroyed into the GvrDelegateProvider, and it refactors out some instances of using the GVR api in a non-threadsafe way.

Some minor functional changes may be visible with this patch - namely that we no longer (possibly) send a DisplayConnected event for a display that isn't ready yet due to the gvr api not being available. This should be an improvement in all cases.

BUG= 674594 ,  655297 

Review-Url: https://codereview.chromium.org/2658643003
Cr-Commit-Position: refs/heads/master@{#447643}

[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/chrome/browser/android/vr_shell/BUILD.gn
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/chrome/browser/android/vr_shell/non_presenting_gvr_delegate.cc
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/chrome/browser/android/vr_shell/non_presenting_gvr_delegate.h
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/chrome/browser/android/vr_shell/vr_compositor.cc
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/chrome/browser/android/vr_shell/vr_compositor.h
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/chrome/browser/android/vr_shell/vr_gl_thread.h
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/chrome/browser/android/vr_shell/vr_shell.cc
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/chrome/browser/android/vr_shell/vr_shell.h
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/chrome/browser/android/vr_shell/vr_shell_delegate.cc
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/chrome/browser/android/vr_shell/vr_shell_delegate.h
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/chrome/browser/android/vr_shell/vr_shell_gl.cc
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/chrome/browser/android/vr_shell/vr_shell_gl.h
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/device/vr/android/gvr/gvr_delegate.h
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/device/vr/android/gvr/gvr_device.cc
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/device/vr/android/gvr/gvr_device.h
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/device/vr/android/gvr/gvr_device_provider.cc
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/device/vr/android/gvr/gvr_device_provider.h
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/device/vr/android/gvr/gvr_gamepad_data_fetcher.cc
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/device/vr/android/gvr/gvr_gamepad_data_fetcher.h
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/device/vr/test/fake_vr_device.cc
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/device/vr/test/fake_vr_device.h
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/device/vr/vr_device.cc
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/device/vr/vr_device.h
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/device/vr/vr_display_impl.cc
[modify] https://crrev.com/4c6465c3b85e664ca700e1c04bebf637c7846243/device/vr/vr_display_impl.h

The only remaining thread-unsafe GVR API usages are now in the gamepad API.

Great, thanks! Should we open a separate bug and assign the relevant components so we can close this one as having solved most issues?

File  issue 687992 .